The present invention is generally directed to a method for heat treating biological tissues. More particularly, the present invention is directed to a method for applying a pulsed energy source to biological tissue to stimulate activation of heat shock proteins and facilitate protein repair without damaging the tissue.
The inventors have discovered that there is a therapeutic effect to biological tissue, and particularly damaged or diseased biological tissue, by controllably elevating the tissue temperature up to a predetermined temperature range while maintaining the average temperature rise of the tissue over several minutes at or below a predetermined level so as not to permanently damage the target tissue. It is believed that raising the tissue temperature in such a controlled manner selectively stimulates heat shock protein activation and/or production and facilitation of protein repair, which serves as a mechanism for therapeutically treating the tissue.
Heat shock proteins (HSPs) are a family of proteins that are produced by cells in response to exposure to stressful conditions. Production of high levels of heat shock proteins can be triggered by exposure to different kinds of environmental stress conditions, such as infection, inflammation, exercise, exposure of the cell to toxins, starvation, hypoxia, or water deprivation.
It is known that heat shock proteins play a role in responding to a large number of abnormal conditions in body tissues, including viral infection, inflammation, malignant transformations, exposure to oxidizing agents, cytotoxins, and anoxia. Several heat shock proteins function as intra-cellular chaperones for other proteins and members of the HSP family are expressed or activated at low to moderate levels because of their essential role in protein maintenance and simply monitoring the cell's proteins even under non-stressful conditions. These activities are part of a cell's own repair system, called the cellular stress response or the heat-shock response.
Heat shock proteins are typically named according to their molecular weight. For example, Hsp60, Hsp70 and Hsp80 refer to the families of heat shock proteins on the order of 60, 70 and 80 kilodaltons in size, respectively. They act in a number of different ways. For example, Hsp70 has peptide-binding and ATPase domains that stabilize protein structures in unfolded and assembly-competent states. Mitochondrial Hsp60s form ring-shaped structures facilitating the assembly of proteins into native states. Hsp90 plays a suppressor regulatory role by associating with cellular tyrosine kinases, transcription factors, and glucocorticoid receptors. Hsp27 suppresses protein aggregation.
Hsp70 heat shock proteins are a member of extracellular and membrane bound heat-shock proteins which are involved in binding antigens and presenting them to the immune system. Hsp70 has been found to inhibit the activity of influenza A virus ribonucleoprotein and to block the replication of the virus. Heat shock proteins derived from tumors elicit specific protective immunity. Experimental and clinical observations have shown that heat shock proteins are involved in the regulation of autoimmune arthritis, type 1 diabetes, mellitus, arterial sclerosis, multiple sclerosis, and other autoimmune reactions.
Accordingly, it is believed that it is advantageous to be able to selectively and controllably raise a target tissue temperature up to a predetermined temperature range over a short period of time, while maintaining the average temperature rise of the tissue at a predetermined temperature over a longer period of time. It is believed that this induces the heat shock response in order to increase the number or activity of heat shock proteins in body tissue in response to infection or other abnormalities. However, this must be done in a controlled manner in order not to damage or destroy the tissue or the area of the body being treated. The present invention fulfills these needs, and provides other related advantages.